Domröse Till, Danz Thomas, Schaible Sophie F, Rossnagel Kai, Yalunin Sergey V, Ropers Claus
Department of Ultrafast Dynamics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
4th Physical Institute - Solids and Nanostructures, University of Göttingen, Göttingen, Germany.
Nat Mater. 2023 Nov;22(11):1345-1351. doi: 10.1038/s41563-023-01600-6. Epub 2023 Jul 6.
The tunability of materials properties by light promises a wealth of future applications in energy conversion and information technology. Strongly correlated materials such as transition metal dichalcogenides offer optical control of electronic phases, charge ordering and interlayer correlations by photodoping. Here, we find the emergence of a transient hexatic state during the laser-induced transformation between two charge-density wave phases in a thin-film transition metal dichalcogenide, 1T-type tantalum disulfide (1T-TaS). Introducing tilt-series ultrafast nanobeam electron diffraction, we reconstruct charge-density wave rocking curves at high momentum resolution. An intermittent suppression of three-dimensional structural correlations promotes a loss of in-plane translational order caused by a high density of unbound topological defects, characteristic of a hexatic intermediate. Our results demonstrate the merit of tomographic ultrafast structural probing in tracing coupled order parameters, heralding universal nanoscale access to laser-induced dimensionality control in functional heterostructures and devices.
通过光来调节材料特性有望在能量转换和信息技术领域带来大量未来应用。诸如过渡金属二硫属化物等强关联材料可通过光掺杂实现对电子相、电荷有序性和层间相关性的光学控制。在此，我们发现在薄膜过渡金属二硫属化物1T型二硫化钽（1T-TaS₂）中，两个电荷密度波相之间的激光诱导转变过程中出现了一种瞬态六重态。引入倾斜系列超快纳米束电子衍射，我们在高动量分辨率下重建了电荷密度波摇摆曲线。对三维结构相关性的间歇性抑制促进了由高密度未束缚拓扑缺陷导致的面内平移有序性的丧失，这是六重态中间体的特征。我们的结果证明了断层超快结构探测在追踪耦合序参量方面的优点，预示着在功能异质结构和器件中对激光诱导维度控制的普遍纳米级访问。
